Dissertations / Theses on the topic 'PTT Fluid'

Les arbres irriguent leurs organes par un système microfluidique complexe qui permet le transfert d’eau sous des pressions hydrostatiques négatives allant de -0.1 à -13 MPa. Dans ces conditions de métastabilité, les arbres vivent avec le risque d’une vaporisation soudaine de leur sève, qui conduit à l’embolie. Après cavitation, la poche de gaz créée croît ensuite par différence de pression et diffuse dans les vaisseaux du xylème à travers des membranes poreuses appelées “ponctuations”. Ces membranes permettent d’assurer le transfert hydrique vasculaire et de lutter contre la propagation de l’embolie gazeuse pouvant conduire à un état létal de la plante. Pour comprendre les mécanismes d’embolie d’air dans le xylème, nous avons pu étudier la structure des ponctuations du peuplier et caractériser par microscopie à force atomique (AFM) leurs propriétés mécaniques. Nous avons fait des expériences de nano-indentation et de flexion sur des échantillons secs et saturés en eau. Les premières expériences semblent montrer que les propriétés mécaniques sont peu affectées par la sorption d’eau (le module d’Young de la membrane primaire est E 0:40 GPa). Nous avons pu établir que le module des ponctuations était inférieur à celui de la paroi vaisseaux du xylème (E 8 GPa). Des expériences de micromoulages ont montré que les membranes des ponctuations se déforment sous l’effet d’une différence de pression. En tenant compte de la présence des parois secondaires, l’analyse par éléments finis de la déformation des ponctuations permet de calculer le module d’Young des membranes qui est identique à celui déterminé en AFM. Nous avons pu mettre en évidence que les mâchoires constituées par les parois secondaires limitent la déformation de la membrane au niveau de l’encastrement près du bord. Des expériences d’injection d’air ont permis de déterminer la pression critique (Pc = 1:8 MPa) et les diamètres critiques des pores présents sur les valves capillaires (dpore 160 nm). La taille des pores estimée est cohérente avec les données de la littérature. Nous avons proposé une première modélisation de la propagation d’une embolie sur la base de l’écoulement de Darcy dans la membrane. L’ensemble des résultats semble montrer que la diffusion de gaz est rendu possible par l’effet conjoint de la déformation de la membrane qui génère l’ouverture des pores diminuant ainsi la pression critique de passage du gaz et de la rupture des ponts capillaires présents dans les pores de la membrane.

Orientadores: José Roberto Nunhez, Nicolas Spogis<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-22T07:47:05Z (GMT). No. of bitstreams: 1 Vergel_JoseLuisGomez_M.pdf: 8156840 bytes, checksum: f0b5d7b4b0875d4716285f8ec3ce5fa2 (MD5) Previous issue date: 2013<br>Resumo: O uso de malhas não estruturadas recentemente tem recebido uma considerável atenção para discretização do domínio computacional em simulações CFD (Vakili & Esfahany, 2009; Cabrales, et al., 2011). A malha não estruturada (comumente tetraédricas) permite uma adequada adaptação em geometrias irregulares e uma geração automática na maioria dos softwares comerciais em CFD. Na literatura constantemente tem sido sugerido que as malhas hexaédricas são preferidas as tetraédricas, porém esta última pode ser usada, desde que alguns cuidados sejam tomados para proporcionar uma boa representação do fenômeno físico do problema. Alguns trabalhos recentemente publicados mostram que as malhas tetraédricas quando utilizadas com cuidado, podem obter resultados satisfatórios (Spogis & Nunhez, 2009). A maioria dos trabalhos desenvolvidos com uso da simulação CFD para processos de mistura utilizam malha hexaédrica, enquanto os resultados obtidos com malhas tetraédricas não possuem a mesma aprovação (Joaquim Junior et al., 2007), parte deste trabalho esta focado em mostrar que elas podem fornecer bons resultados em simulações de processos de mistura. Outro objetivo desse trabalho é mostrar o efeito do refinamento em malhas tetraédricas. Investigou-se a influência dos elementos prismáticos perto da parede sobre parâmetros globais, tais como o número de potência e número de bombeamento. Foi também realizada uma análise inicial da sensibilidade de alguns modelos de turbulência e esquemas de discretização sobre o campo de fluxo produzido. Além disso, simulações com diferentes refinamentos de malha foram feitas usando a abordagem de múltiplos sistemas de referência (MFR); enquanto em outros casos foi proporcionada uma abordagem de malhas deslizantes (SG) no impelidor. Os esquemas de discretização foram limitados aos esquemas Upwind, High resolution e blend fator, uma vez que esquemas diferentes não funcionam adequadamente com elementos tetraédricos. O software comercial de CFD CFX 14.0 foi utilizado para simular os resultados. Um impelidor de pás inclinadas (PBT 45°, com bombeamento para baixo) foi simulado em regime turbulento. Os resultados obtidos pelas simulações CFD para o número de potência e bombeamento, e perfil da componente axial da velocidade são discutidos e comparados com dados experimentais (Machado et al. et al., 2011). A velocidade foi medida usando a técnica PIV (Particle Image Velocimetry). Uma significativa influencia foi observada em alguns parâmetros na determinação de importantes variáveis nos processos de mistura. De forma geral, a predição do perfil da velocidade é influenciada, de alguma forma, pela resolução da malha, pelo modelo de turbulência e pelo esquema de discretização<br>Abstract: The use of non-structured meshes has received recently considerable attention for discretization of the computational domain in CFD simulations (Vakili & Esfahany, 2009; Cabrales et al., 2011). The non-structured meshes (the most common are tetrahedral) allow adequate adaptation of irregular geometries and easy use of automated algorithms for mesh generation in most commercial CFD software. It has been consistently suggested in the literature that hexahedral meshes are preferred over tetrahedral. However, they can be used, provided that some care is taken to provide a good representation of the physical phenomena of the problem. Recently published works have been proving that if they are used with care, satisfactory results are obtained (Spogis & Nunhez, 2009). Most of works developed with the use of CFD simulation for mixing processes use hexahedral and to date tetrahedral do not have the same acceptance of hexahedral (Joaquim Junior et al., 2007) and part of this work is aimed at showing that they can provide good results when simulating mixing processes. Another objective of this work is to show the effect of mesh refinement in tetrahedral meshes. It is investigated the influence of the prismatic elements near wall on global parameters such as the Power and Flow numbers. An initial analysis of the sensitivity of some turbulence models (Standard k-? model, the shear stress transport (SST) and BSL-Reynolds stress model) and the discretization scheme on the flow field produced were also carried out in this work. In addition, simulations with different mesh resolutions were made using the multiple reference frame (MFR) approach; whereas other cases a sliding mesh modeling was provided for the impeller. The discretization schemes were limited to upwind, high resolution and blend factor, since other schemes do not work well with tetrahedral. The commercial CFD software CFX 14.0 was used to simulate the results. A pitched blade turbine (PBT 45°, down-pumping), was simulated in turbulent flow. The results obtained for the Power and Flow numbers, the axial velocity profile component of the model in CFD are discussed and compared with experimental data (Machado et al. et al., 2011). The velocity was measured using the PIV technique (Particle Image Velocimetry). A significant influence of some parameters is observed on the determination of some important variable mixing. In general, the predictions of the velocity profile are influenced in some way by the resolution of the mesh, turbulence model and the discretization scheme<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

L'objectif de cette thèse est l'étude du bruit propre d'origine hydrodynamique au niveau de l'antenne d'étrave d'un sous-marin pour des fréquences comprises entre 10 Hz et quelques kHz. Dans cette optique, trois problématiques particulières doivent être étudiées : la modélisation du comportement vibro-acoustique des structures en fluide lourd, l'intégration de l'excitation couche limite turbulente (CLT) dans les modèles numériques déterministes et la mesure de la réponse d'une structure sous écoulement turbulent. Le premier chapitre est consacré à la synthèse bibliographique des différentes méthodes existantes pour étudier de tels problèmes. Dans un second chapitre, nous présentons la méthode PTF (Patch Transfer Functions), qui est une approche par sous-structuration de domaines permettant l'étude des problèmes vibro-acoustiques en basses et moyennes fréquences. Cette méthode n'ayant été appliquée qu'en fluide léger, l'un des enjeux de ce chapitre est d'étudier son applicabilité en fluide lourd et de mettre en lumière d'éventuels points de blocage. Nous montrons ainsi que des problèmes de convergence de la méthode apparaissent en fluide lourd. Pour pallier ces difficultés, nous présentons, dans le troisième chapitre, deux stratégies de calcul permettant d'accélérer la convergence globale de la méthode. Le quatrième chapitre propose une application de la méthode PTF pour caractériser la réponse vibro-acoustique en fluide lourd d'une structure soumise à une CLT et couplée à un milieu fluide extérieur et à une cavité acoustique, encombrée par des structures déformables. Pour traiter ce problème, nous complétons, tout d'abord, le modèle PTF par l'introduction de l'excitation CLT dans les modèles déterministes, à partir d'une décomposition de l'interspectre des fluctuations de pression pariétale sur une base d'ondes planes décorrélées. Nous présentons, ensuite, le calcul de l'impédance de rayonnement par pavé pour des surfaces de couplage de géométrie quelconque, ainsi qu'un modèle d'encombrement permettant, à partir de considérations physiques, de tenir compte simplement de la complexité structurale de structures encombrant une cavité acoustique. Cette application nous permet de montrer que l'influence de l'encombrement des cavités sur la réponse vibro-acoustique du système ne peut pas être négligée, lorsque l'on s'intéresse à l'étude du bruit hydrodynamique au niveau d'une antenne d'étrave de sous-marin. Dans le cinquième chapitre, nous développons une technique expérimentale permettant de caractériser le comportement des structures sous écoulement turbulent. Cette technique est basée sur la décomposition en ondes planes décorrélées présentée au chapitre 4 et nécessite la génération de champs de pression pariétale correspondant à ceux que l'on obtiendrait à partir d'ondes propagatives et évanescentes pour tenir compte des caractéristiques spectrales de la CLT. Pour cela, nous utilisons une antenne de monopôles acoustiques, dont nous déterminons numériquement les principaux paramètres (taille, nombre de monopôles et distance antenne paroi). Le nombre de monopôles augmentant avec la fréquence, la mise en oeuvre de cette méthode peut s'avérer délicate. Pour contourner cette difficulté, nous présentons le principe de l'antenne synthétique, dont la validation expérimentale est étudiée dans le dernier chapitre.

Der ehemalige Salzbergbau im Raum Staßfurt führt seit dem 19. Jahrhundert zu Subrosion und teils bruchhaften Deformationen und damit verbundenen Senkungen und Vernässungen im Stadtgebiet. Im Rahmen eines Forschungsverbundvorhabens unter Federführung der BGR sollen in dieser Arbeit die grundlegenden strömungsdynamischen Prozesse im Salinar und Deckgebirge der betroffenen geologischen Formationen aufgeklärt werden. An Bohrkernen aus den entsprechenden Bereichen werden Durchflussexperimente durchgeführt und die Fluiddynamik im Inneren der Proben mittels Positronen-Emissions-Tomographie dreidimensional dargestellt. In Kooperation mit der Bundesanstalt für Materialforschung- und prüfung Berlin und dem Geologischen Institut der Johannes-Gutenberg Universität Mainz werden diese PET-Messungen der Fluiddynamik mit hochauflösenden computertomographischen Messungen der internen Struktur der Proben in Übereinstimmung gebracht. Die beobachteten Fließmuster sollen mittels einer Lattice-Boltzmann-Simulation nachvollzogen und dadurch das grundlegende Verständnis der Strömungsdynamik in diesen Gesteinen erweitert werden. Langfristig soll dies zu einer Verbesserung des Verständnisses der Grundwasserdynamik auf regionaler Ebene führen.

Cette thèse s’inscrit dans le projet Fond Unique Interministériel (FUI) HydroSafeTire, dédié à l’étude du phénomène de l’hydroplanage. Au cours d’une précédente thèse sur le sujet au sein du laboratoire, l’étude de ce phénomène a été réalisée via un couplage fluide/structure SPH/FE en utilisant le solveur FE Abaqus développé par Simulia. Des effets tels que la hauteur d’eau, la vitesse du véhicule ou encore l’usure du pneumatique ont ainsi été investigués, montrant que les tendances observées durant les expérimentations étaient retrouvées numériquement. A l’issue de ces travaux, il a donc été décidé d’utiliser le solveur structure FE développé spécifiquement par Michelin (en collaboration avec le GIREF) pour ses applications, afin de tirer profit des avantages de ce solveur pour le problème spécifique de l’hydroplanage. Ainsi dans cette thèse, la première étape est la validation du couplage SPH/FE avec ce code structure sur des cas tests académiques. L’obtention d’un bon compromis précision des résultats / temps de restitution des simulations constitue un enjeu majeur, en particulier dans un contexte industriel. Ainsi, cette thèse s’articule autour de trois axes. Premièrement, un travail sur la consistance des schémas SPH utilisant une méthode de désorganisation particulaire est effectué, en parallèle d’un travail sur la méthode de désorganisation en elle même. Ensuite, un modèle de décollement de jets de surface libre est proposé, compatible avec la prise en compte des effets de succion. Enfin, différents schémas de couplage SPH/FE à pas de temps différés sont étudiés, avec une application à l’hydroplanage<br>This PhD thesis takes place in the Fond Unique Interministériel (FUI) HydroSafeTire project, dedicated to the study of the hydroplaning phenomenon. During a previous PhD thesis regarding this topic in the lab., the hydroplaning phenomenon has been investigated via a fluid/structure SPH/FE coupling, using the FE solver Abaqus developed by Simulia. Physical effects such as the water height, the velocity of the vehicle and the tire wear have been studied, showing that the tendencies experimentally observed were retrieved in the simulations. Therefore, it has been decided to use the FE structure solver specifically developed by Michelin for their tire applications, in order to take benefits of this solver for the specific hydroplaning problem. Then, in the present PhD thesis, the first step is the validation of the SPH/FE coupling, using this FE code, on academic test cases. The compromise between the accuracy of the results and the restitution time of the simulations is of paramount importance, particularly in an industrial context. Thus, three main topics are investigated in this work. Firstly, the consistency of SPH schemes using a Particle Shifting Technique (PST) is studied, in addition to a work on the PST itself. Then, a model of flow separation is proposed, compatible with suction effects. Finally, different coupling schemes SPH/FE using differed time-steps are studied, with an hydroplaning application

La enfermedad de Alzheimer (EA) se caracteriza neuropatológicamente por la presencia de depósitos extracelulares de ß-amiloide (Aß) y ovillos neurofibrilares intracelulares (proteína tau fosforilada, p-tau) así como fenómenos inflamatorios. Estos procesos se asocian con atrofia cerebral, pérdida neuronal y alteraciones funcionales que acaban produciendo deterioro cognitivo y eventualmente un síndrome clínico de demencia. El depósito de amiloide comienzan décadas antes de que se pueda hacer un diagnóstico de demencia e incluso de la aparición de los primeros síntomas, y constituyen lo que se conoce como EA preclínica (Sperling et al., 2011). En la actualidad podemos estudiar los mecanismos fisiopatológicos que ocurren en la EA preclínica a través de biomarcadores (Dubois et al., 2016). Entender las relaciones entre biomarcadores en la EA preclínica es esencial para entender la fisiopatología de la enfermedad y poder desarrollar terapias que ralenticen o frenen su curso. Sin embargo, estas relaciones distan de estar claras, por ejemplo, la relación de la amiloidosis y la estructura cortical dista de es controvertida (Fortea et al., 2014). El objetivo principal de esta tesis fue estudiar las alteraciones corticales estructurales que ocurren en la enfermedad de Alzheimer preclínica. Concretamente, los objetivos fueron 1) estudiar la relación entre Aß y el grosor cortical y sus posibles interacciones con la proteína p-tau, 2) analizar los cambios estructurales corticales longitudinales de la EA preclínica, 3) investigar la microestructura cortical y entender su relación con la macroestructura en el continuum de la enfermedad y, 4) estudiar el impacto local del depósito de amiloide en la estructura cerebral en la EA preclínica. Para la realización de esta tesis se ha contado con bases de datos públicas americanas (Alzheimer’s Disease Neuroimaging Initiative, http://adni.loni.usc.edu/) y con bases de datos españolas (proyecto SIGNAL, https://www.signalstudy.es/). Los resultados de la tesis han conducido a la propuesta de un modelo bifásico de cambios corticales estructurales en la EA preclínica. El depósito de amiloide en ausencia de tau patológico se asocia a un incremento del grosor cortical, una ralentización de la atrofia longitudinal a 2 años y descensos de difusión cortical. Posteriormente, en presencia de tau patológica, y como resultado del efecto tóxico sinérgico o interacción entre procesos patológicos, se produciría una aceleración de la atrofia e incrementos de difusión que se extenderían siguiendo un patrón característico que ha sido definido como la huella cortical de la EA (Dickerson et al., 2009). Los resultados presentados en esta tesis tienen implicación directa en la investigación y en la práctica clínica. En primer lugar, en relación a los modelos de evolución de biomarcadores de la EA (Jack et al., 2013) ya que esta fase temprana de engrosamiento cortical no está contemplada en los modelos actuales. Nuestro modelo ayudaría a integrar los resultados contradictorios previos en la literatura en relación a los efectos del amiloide sobre la estructura cerebral. Los modelos actuales, no contemplan la interacción/sinergia entre biomarcadores que rigen el mencionado proceso bifásico. En segundo lugar, los resultados tienen implicaciones en el diseño de los ensayos clínicos, tanto en la selección de pacientes como en el uso subrogado de la resonancia como marcador de eficacia, ayudando a entender algunos resultados inesperados de los ensayos clínicos previos con inmunoterapia anti-amiloidea. Finalmente, la difusión cortical podría ser un marcador precoz en el curso de la EA. Futuros estudios multimodales de resonancia magnética y líquido cefalorraquídeo que incorporen PET de inflamación y de Tau con seguimientos longitudinales serán claves para seguir estudiando los procesos fisiopatológicos que subyacen la EA preclínica.<br>The Alzheimer’s disease (AD) neuropathological hallmarks are the presence of extracellular amyloid ß (Aß) deposition and intracellular neurofibrillary tangles (hyperphosphorilated tau protein) as well as inflammation phenomena. These processes are associated with cerebral atrophy, neuronal loss and functional alterations which lead to cognitive dysfunction and, eventually, a clinical syndrome of dementia. These pathophysiological processes begin decades before the diagnosis of the clinical dementia even before the appearance of the first clinical symptoms, and constitute the preclinical AD (Sperling et al, 2011). Nowadays we can study the pathophysiological mechanisms that occur in preclinical AD through biomarkers (Dubois et al., 2016). It is crucial to understand the relationships between biomarkers in preclinical AD to further understand the disease pathophysiology and be able to develop treatments that could slow down or stop its course. However, these relationships are not clear, for example, the relationship between brain amyloidosis and brain structure is controversial (Fortea et al., 2014). The objective of this thesis was to study the cortical structural alterations that occur in preclinical AD. Specifically, 1) to study the relationship between Aß and cortical thickness and its potential interactions with p-tau, 2) to analyze the 2-year cortical longitudinal changes in preclinical AD, 3) to investigate cortical microstructure and understand its relationship with brain macrostructure in the disease continuum and, 4) to assess the local impact of amyloid deposition in brain structure in preclinical AD. In this thesis, we have used data from a public American database (Alzheimer’s Disease Neuroimaging Initiative, http://adni.loni.usc.edu/) and from a Spanish multicentric cohort (proyecto SIGNAL, https://www.signalstudy.es/). The results of this thesis have conducted to the proposal of a biphasic model of structural cortical changes in preclinical AD. Amyloid deposition in the absence of pathological tau levels would be associated with increased cortical thickness, less 2-year longitudinal cortical thinning and cortical diffusivity decreases. Then, in the presence of pathological tau levels, and as a result of the synergic toxic effect or interaction between pathologic processes, there would be an atrophy acceleration and cortical diffusivity increases that would spread following a pattern that has been described as the AD-signature (Dickerson et al., 2009). The results presented in this thesis have direct research and clinical implications. First, they impact on the models of biomarker evolution in AD (Jack et al., 2013), as the cortical thickening phase is not contemplated in previous models. Our model would help to understand previous contradictory results in the literature that assessed the effect of amyloid on brain structure. Current models do not take into account the interaction/synergy effect between biomarkers that define the aforementioned biphasic process. Second, our results have relevance in the design of clinical trials, both in the selection of patients and in the use of MRI as a surrogate marker of efficacy, and might help explain some unexpected results in previous anti-amyloid immunotherapy trials. Finally, cortical diffusivity could be an early marker in the AD course. Further multimodal studies that incorporate tau- and inflammation-PET with longitudinal follow-ups are crucial to further investigate the pathophysiological process that underlies preclinical AD.

Los tanques agitadores son ampliamente utilizados en diferentes industrias, en donde la eficiencia de las operaciones de mezclado tiene un impacto tanto en los costos como en la calidad del proceso, si a esto se le añade que para poder mantener la competitividad en el mercado, el tiempo de desarrollo del producto debe ser el menor posible y a un bajo costo, por ese motivo es necesario optar por nuevas formas para realizar nuevos diseños. En muchas empresas fabricantes de gran envergadura, el uso software de optimización se está convirtiendo en una herramienta ideal para conseguir estos objetivos. En este trabajo se utilizó las herramientas computacionales ANSYS CFX, MECHANICAL y DESIGN EXPLORATION para realizar una metodología que permita realizar la simulación numérica tanto a nivel de fluidos y estructural como para realizar la optimización de un modelo de tanque agitador. Para la elaboración de este procedimiento se optó por variar en un rango determinado ciertos parámetros geométricos y de funcionamiento. En el estudio fluido dinámico se trabajó tres fluidos: agua, metanol y aire, en donde los dos primeros se modelaron como “multicomponentes” es decir como fluidos miscibles, mientras que la interacción con el aire se modelo como “superficie libre”. Para esto, se utilizó el modelo de turbulencia SST (Shear Stress Transport), el cual demostró en un estudio anterior ser el que más se ajusta al ser contrastado con resultados experimentales, además se empleó los modelos de “marco de referencia móvil (MRF)” y de “Frozen Rotor” para tratar la interacción entre las partes móviles (rotor) y partes estáticas (tanque y deflectores). Para el análisis estructural se utilizó la metodología de interacción fluido-estructura (FSI) del tipo “unidireccional (one-way)” para determinar los esfuerzos y deformaciones en cada diseño. Finalmente, se utilizó el método de la superficie de respuesta (RSM) como base para la optimización, donde se utilizó un algoritmo estocástico (MOGA) como buscador de soluciones óptimas en el modelo del tanque agitador parametrizado, el cual consta de tres variables de entrada (ángulo de alabe, altura de impulsor y velocidad de rotación) y dos funciones objetivos: maximizar grado de mezcla y minimizar la potencia consumida. El presente estudio demuestra que la velocidad y el ángulo son los parámetros más incidentes en las funciones objetivas mencionadas anteriormente y que al variar estos parámetros se pueden obtener mejoras significativas en los resultados. En este estudio en particular se encontró que el ángulo de 60 grados y una altura de 300mm con respecto al tanque, mejora en un 8% y 36% el consumo de potencia y grado de mezcla respectivamente, para las configuraciones del tanque dadas.<br>Tesis

Ce travail de thèse porte sur les outils statistiques pour l'évaluation des maxima de charges de sloshing dans les cuves de méthaniers. Selon les caractéristiques du navire, son chargement et les conditions de navigation, un ballotement hydrodynamique est observé à l'intérieur des cuves, phénomène communément appelé sloshing. La détermination des charges qui s'appliquent à la structure est basée sur des mesures de pression d'impact au moyen d'essais sur maquette. Les maxima de pression par impact, extraits des mesures, sont étudiés. La durée d'un essai est équivalente à 5 heures au réel et insuffisante pour déterminer des maxima de pression associés à de grandes périodes de retour (40 ans). Un modèle probabiliste est nécessaire pour extrapoler les maxima de pression. Le modèle usuel est une loi de Weibull. Comme ce sont les valeurs extrêmes des échantillons qui nous intéressent, les ajustements sont aussi effectués par les lois des valeurs extrêmes et de Pareto généralisées via les méthodes de maximum par bloc et d'excès au-dessus d'un seuil.L'originalité du travail repose sur l'emploi d'un système alternatif, plus pertinent pour la capture des maxima de pression et d'une quantité de 480 heures de mesures disponible pour les mêmes conditions d'essai. Cela fournit une distribution de référence pour les maxima de pression et nous permet d'évaluer la pertinence des modèles sélectionnés. Nous insistons sur l'importance d'évaluer la qualité des ajustements par des tests statistiques et de quantifier les incertitudes sur les estimations obtenues. La méthodologie fournie a été implémentée dans un logiciel nommé Stat_R qui facilite la manipulation et le traitement des résultats<br>This thesis focuses on statistical tools for the assessment of maxima sloshing loads in LNG tanks. According to ship features, tank cargo and sailing conditions, a sloshing phenomenon is observed inside LNG tanks. The determination of sloshing loads supported by the tank structure is derived from impact pressure measurements performed on a test rig. Pressure maxima per impact, extracted from test measurements, are investigated. Test duration is equivalent to 5 hours in full scale. This duration is not sufficient to determine pressure maxima associated with high return periods (40 years). It is necessary to use a probabilistic model in order to extrapolate pressure maxima. Usually, a Weibull model is used. As we focus on extreme values from samples, fittings are also performed with the generalized extreme value distribution and the generalized Pareto distribution using block maximum method and peaks over threshold method.The originality of this work is based on the use of an alternate measurement system which is more relevant than usual measurement system to get pressure maxima and a 480 hours measured data available for same test conditions. This provides a reference distribution for pressure maxima which is used to assess the relevance of the selected probabilistic models. Particular attention is paid to the assessment of fittings quality using statistical tests and to the quantification of uncertainties on estimated values.The provided methodology has been implemented in a software called Stat_R which makes the manipulation and the treatment of results easier

La thérapie photodynamique (PDT) est une technique utilisée cliniquement pour traiter certaines maladies de la peau, la dégénérescence maculaire liée à l’âge et certains types de cancer. Elle fait intervenir trois composants : une molécule photosensible ou photosensibilisateur (PS), la lumière et l’oxygène. Après administration du PS, celui-ci va se localiser plus ou moins sélectivement dans les zones tumorales où il est alors activé par irradiation lumineuse à une longueur d’onde et une puissance données. Ceci engendre la formation d’espèces réactives de l’oxygène (ROS) très réactives, dont l'oxygène singulet1 O2, qui entraînent la destruction des tissus tumoraux par nécrose ou apoptose. Afin d’améliorer la sélectivité du traitement, différentes pistes sont actuellement exploitées dont l’élaboration de « photodynamic molecular beacons » (PMB). Dans un PMB, le photosensibilisateur (PS) est associé via un peptide à un inhibiteur 1O2, appelé quencher. Ce quencher inhibe la formation d’1O2 tant que le composé n’a pas atteint sa cible. Une fois la zone cancéreuse atteinte, des enzymes spécifiques clivent le peptide, libérant ainsi le PS qui retrouve alors sa capacité à former de l’1O2. Trouver un couple PS/quencher adéquat reste un challenge en PDT. Les propriétés photophysiques particulières des caroténoïdes et leur aptitude à inhiber la production d’1O2 font de ces derniers des quenchers potentiellement utilisables pour l’élaboration de PMBs. Chez les plantes, les caroténoïdes (carotènes et xanthophylles) sont des pigments associés à la photosynthèse, qui ont deux rôles principaux : un rôle de collecteur de lumière et un rôle photoprotecteur en protégeant le(s) système(s) photosynthétique(s) contre les dommages photooxydatifs liés à une exposition trop intense à la lumière. Ceci s’opère, entre autre, via le cycle des xanthophylles. Cette aptitude à capter de l’énergie présente un intérêt potentiel à ne pas négliger dans la perspective de la conception de PMB utilisables en thérapie photodynamique. Dans le cadre de cette thèse en co-tutelle avec la Faculté des Sciences de Bizerte nous avons ciblé les caroténoïdes présents dans trois fruits produits en Tunisie à savoir les kakis (Diospyros kaki L.), les abricots (Prunus armeniaca L.) et les pêches (Prunus persica L.) connus pour leur richesse globale en ces pigments. Divers procédés d’extractions ont été étudiés : (i) L’extraction de type Soxhlet par solvants organiques à pression atmosphérique, utilisée comme référence, (ii) l'extraction accélérée par solvant organique (ASE : Accelerated solvent Extraction) effectuée sous pression, enfin (iii) l'extraction par CO2 supercritique avec l’éthanol comme cosolvant. Pour ces deux derniers procédés, une approche par plan d’expériences (surfaces de réponses) a été utilisée pour identifier les facteurs clé et les conditions optimales d’extractions de divers caroténoïdes (pression, température, débit, % de cosolvant, temps, nombre de cycles). L'analyse par chromatographie liquide à haute performance couplée à la détection UV-Visible et à la spectrométrie de masse a ensuite permis l'identification et la quantification des caroténoïdes présents dans les extraits obtenus, permettant ainsi de comparer les profils caroténoïdiques propres à chaque fruit et les performances de chaque procédé d’extraction. Cette étude ayant révélé un profil caroténoïdique particulièrement intéressant chez le kaki par rapport aux autres fruits, une extraction et une purification des caroténoïdes de ce fruit par chromatographie liquide haute pression préparative a ensuite été effectuée afin de disposer d’une quantité suffisante de chaque caroténoïde, et parfois de leurs isomères conformationnels, en vue de l’étude de leurs propriétés photophysiques (absorption, émission de fluorescence, inhibition d’1O2) et de l’évaluation de leur intérêt potentiel en tant que quencher d’1O2 dans un édifice de type PMB<br>Photodynamic therapy (PDT) is a clinically used technique for treating skin diseases, age-relatedmacular degeneration but mainly some types of cancer. PDT involves three components: a photosensitive molecule named photosensitizer (PS), light and oxygen. After administration of the PS, this one will be located more or less selectively in tumoral regions where it is activated by light irradiation at appropriate wavelength and power. This leads to the formation of highly reactive and cytotoxic reactive oxygen species (ROS), especially singlet oxygen, resulting in the destruction of the tumor by necrosis or apoptosis. To improve the treatment selectivity, different strategies are being exploited, one of which is the development of "photodynamic molecular beacons" (PMB). In PMB the photosensitizer is linked via a peptide to an inhibitor of 1O2 (quencher). This quencher inhibits the formation of 1O2 as long as the compound has not reached its target, namely cancer cells. In order to inhibit the toxicity of the PS in non-target cells and restore toxicity only close to the biological target, it is necessary to find an adequate PS/quencher couple. This remains a challenge for PDT. Carotenoids are interesting candidates due to their specific photophysical properties and ability to inhibit 1O2, which makes them potential quenchers for building PMBs. In plants, carotenoids (carotenes and xanthophylls) are pigments involved in the photosynthesis, in which they play two main roles: a light collecting role and a protecting role by preserving the photosynthetic systems against photoxydative damages induced by a too intense light exposure. This protection can for instance occur via the well-known xanthophylls cycle. This capacity to catch energy presents a potential interest that should not be neglected in the framework of the design of PMBs usable in photodynamic therapy. Within the framework as part of this PhD thesis in Cotutelle with the Faculty of Sciences of Bizerte, we focused on carotenoids from three fruits produced in Tunisia: persimmon (Diospyros kaki L.), apricot (Prunus armeniaca L.) and peache (Prunus persica L.), known for their global richness in these natural pigments. Three extraction processes were investigated: (i) the Soxhlet extraction based on the use of organic solvent at atmospheric pressure and used as reference, (ii) the accelerated solvent extraction (ASE) using organic solvent under high pressure, and (iii) the supercritical fluid extraction (SFE) using supercritical CO2 and ethanol as cosolvent. For these two last processes, a design of experiments (Surface Response Design) was used to identify the key factors and optimal extraction conditions of various carotenoids (pressure, temperature, flow, % cosolvent, time, number of cycles). Then, HPLC-PDA coupled with mass spectrometry (MS) enabled the identification and quantification of carotenoids from the extracts. Thus it was possible to compare the profiles in carotenoids content from each fruit as well as the performances of each extraction process. This study showed that the carotenoidic profile in the persimmon was the most interesting as compared to the profiles in the two other fruits. Extraction and purification of the carotenoids from persimmon by preparative high pressure liquid chromatography were then performed in order to have a sufficient amount of each carotenoid and sometimes of their conformational isomers. We finally performed a study of their photophysical properties (absorption, fluorescence emission, 1O2 inhibition) in order to evaluate their potential as 1O2 quencher in molecular construction such as a PMB

Increased oil prices and environmental issues have increased a need of loweringthe emissions from and the fuel consumption in heavy construction machines. Anatural solution to these issues is a lowered input power through downsizing ofthe engine. This implies a demand on higher transmission efficiency, in order tominimize the intrusion on vehicle performance. More specifically, alternatives tothe conventional torque converter found in heavier applications today, must beinvestigated. One important part of this is the task of controlling the transmissionwithout jeopardising the advantages associated with the torque converter, such asrobustness and controllability.In this thesis, an alternative transmission concept for a backhoe loader is investigated.The studied concept is referred to as a 2-mode Jarchow power-splittransmission, where a mechanical path is added to a hydrostatic transmission inorder to increase transmission efficiency. The concept is evaluated in computerbased simulations as well as in hardware-in-the-loop simulations, where a physicalhydrostatic transmission is exposed for the loads caused by the vehicle duringvarying conditions. The loads are in turn simulated according to developed modelsof the mechanical parts of the vehicle drive line.In total, the investigated concept can be used instead of the torque converterconcept, if the hydrostatic transmission is properly controlled. The results alsoshow that there is a high possibility that the combustion engine in the backhoeloader can be downsized from 64 kW to 55 kW, which would further increase thefuel savings and reduce the emissions.

Made available in DSpace on 2014-12-17T14:09:13Z (GMT). No. of bitstreams: 1 AlvaroBN_TESE.pdf: 1929903 bytes, checksum: 92f40cf4d3b6ab5536ad5ad3d2aa192a (MD5) Previous issue date: 2012-02-29<br>The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.<br>O presente trabalho proporciona uma metodologia que d? um car?ter preditivo ?s simula??es computacionais baseadas em modelos detalhados da geometria porosa de um meio. N?s utilizando o software FLUENT para investigar o escoamento de um fluido newtoniano viscoso atrav?s de um meio fractal aleat?rio que simplifica um meio poroso desordenado bidimensional representando um reservat?rio de petr?leo. Este modelo fractal ? formado por obst?culos de diversos tamanhos, cuja fun??o de distribui??o segue uma lei de pot?ncia, onde o expoente ? definido como sendo a dimens?o fractal de fracionamento Dff do modelo e caracteriza o processo de fragmenta??o desses obst?culos. Eles s?o aleatoriamente dispostos em um canal retangular. O processo de modelagem incorpora conceitos modernos, leis de escala, para analisar a influ?ncia das heterogeneidades encontradas nos campos da porosidade e da permeabilidade de tal maneira que se possa caracterizar o meio em fun??o de suas propriedades fractais. Este procedimento permite analisar numericamente as medidas da permeabilidade k e do coeficiente de arrasto Cd propondo rela??es, tipo lei de pot?ncia, para essas propriedades sobre v?rios esquemas de modelagem. O prop?sito desta pesquisa ? estudar a variabilidade proporcionada por estas heterogeneidades onde o campo de velocidade e outros detalhes da din?mica dos fluidos viscosos s?o obtidos resolvendo numericamente as equa??es da continuidade e de Navier-Stokes no n?vel de poros e observar como a dimens?o fractal de fracionamento do modelo pode afetar as suas propriedades hidrodin?micas. Neste estudo foram consideradas duas classes de modelos, modelos com porosidade constante, MPC, e modelos com porosidade vari?vel, MPV. Os resultados permitiram-nos encontrar rela??es num?ricas entre a permeabilidade, coeficiente de arrasto e os par?metros geom?tricos do modelo. Com base nestes resultados num?ricos propusemos rela??es de escala envolvendo os par?metros relevantes do fen?meno. Nesta pesquisa foram determinadas equa??es anal?ticas para Dff em fun??o dos par?metros geom?tricos dos modelos. Constatamos tamb?m uma rela??o entre a permeabilidade e o coeficiente de arrasto onde uma ? inversamente proporcional ? outra. Quanto ? diferen?a de comportamento ela ? mais marcante nas classes de modelos MPV. Isto ?, o fato da porosidade variar nestes modelos constitui um fator adicional que desempenha um papel significativo na an?lise de fluxo. Finalmente, os resultados encontrados se mostraram consistentes e satisfat?rios, o que demonstra a efic?cia da referida metodologia para todas as aplica??es analisadas nesta pesquisa.

碩士<br>逢甲大學<br>紡織工程所<br>95<br>In current industrial textile dyeing processes, large amounts of wastewater are produced. This is an environmental burden and, due to the ever more stringent regulations on water pollution, also an economical problem. Only 「Industrial waste minimization」 can give consideration to environment- friendly. Now we have the notion of 「Reduce」、「Reuse」 and 「Recircle」 to environmental protection and economic development. The use of super- critical carbon dioxide as dyeing medium solves this problem: the CO2 and the residual dye remaining in the dye bath after the process can easily be separated and both can be recycled. For reach 「Green Production」, this research of using Cationic surfactant KC-3A(Quaternary ammonium salt) recycling C.I. Reactive Blue 4 (DCT type) and C.I. Reactive Blue 19 (VS type) dyes to the original dyeing process and dyeing Tencel®、Nylon 6.6 and PET fabrics with supercritical fluid further. The recycling dyes structure determined by FT-IR. The RRB 4 and RRB 19 recycling dyes dyeing Tencel®、Nylon 6.6 and PET fabrics in exhausting dyeing process. The results were found it has not been possible to dye these fibers, in this medium with good fastness properties and to acceptable color depth. The positive effect of long alkyl of Quaternary ammonium salt recycling dyes is due to an effect of increased molecular weight and due to an effect of reactive groups on the reactivity of the dye–fiber system to diminish where the alkyl chain increases the hydrophobicity of the dye. The experimental result shows the dyeing with these recycling dyes of PET and Nylon6.6 is satisfactory by dyeing in supercritical carbon dioxide with good fastness properties and acceptable color depth. We found that Tencel® was dyed in supercritical carbon dioxide with pre-treatment of the fiber the color depth was higher than on Tencel®. For Tencel®, optimum dyeing results are obtained at 140 ℃（300 bar）；Nylon6.6, optimum dyeing results are obtained at 120 ℃（300 bar）；PET, optimum dyeing results are obtained at 120 ℃（250 bar）.The fixations on PET、Nylon 6.6 and Tencel®, being above 77 ％, were also dependent of pressure and temperature. The wash and rub fastness of all dyeings was rated at between 3-4 and 5.

Positron Emission Tomography (PET) is frequently used for medical imaging. Maturity and flexibility of PET as an imaging technique has expanded its utility beyond the medical domain. It can be used as a tool for fluid flow studies in opaque fluids and for flow within complex geometry where conventional optical flow measurement approaches fail. This study explores the capabilities of PET as flow measurement tool suited to validation of computational fluid dynamic (CFD) predictions. The MicroPET P4 scanner was used to image the diffusion process in flow around a rod bundle geometry similar to that found in a nuclear reactor fuel assembly. The PET data are compared with results from COMSOL CFD simulation and dye injection images. PET image resolution, acquisition speed and sensitivity are also examined in the context of flow measurement.

According to ICH Q8 process analytic technology (PAT) should be established to monitor critical quality attributes (CQAs) during manufacturing processes. Ethinylestradiol (EE) is a highly active and low dosed steroid hormone that is prone to oxidative degradation. The stability of this compound is therefore a critical quality attribute that has to be considered during drug formulation development. Beside the stability of EE, granule particle size and moisture are CQAs influencing the tableting ability of the resulting granules and the stability of EE. Both CQAs should be monitored during the production process. The investigations described in this thesis evaluate the implementation of in-line-sensors for monitoring of particle size (spatial filtering technology, SFT) and granule moisture (microwave resonance technology, MRT) during the fluid bed granulation process and the influence of process-variations on the stability of EE. The aim of these investigations was to develop an effective and mild fluid bed granulation process for a new model formulation based on microcrystalline cellulose as replacement for lactose as main filler excipient. The EE degradation products 6-alpha-hydroxy-EE, 6-beta-hydroxy-EE, 9(11)-dehydro-EE and 6-oxo-EE were quantified as an index for the stability of EE. It could be demonstrated that the surface of the filler substance influences the stability of EE due to the impact of water molecules. Hence, spraying sequence was determined to be a useful tool to improve the stability of EE. Correlations could be established for 6-oxo-EE with granule moisture and thermic parameters. The implementation of the SFT-sensor in the granulation process was successful. Measurement with the MRT-sensor for monitoring of granule moisture has to be improved.:Chapter I 1 1 Introduction Chapter II 41 2 Materials and Methods Chapter III 54 3 In-line Monitoring of Particle Size in a Fluid Bed Granulator: investigations concerning positioning and configuration of the sensor Chapter IV 72 4 Influence of in line monitored fluid bed granulation process parameters on the stability of Ethinylestradiol Chapter V 90 5 Influence of filler excipients on stability of EE Chapter VI 105 6 Discussion and Conclusion Chapter VII 131 7 Summary Chapter VIII 138 8 Zusammenfassung Reference List 146 Appendix 158

abstract: Gnamma pit is an Australian aboriginal term for weathering pit. A mix of weathering and aeolian processes controls the formation of gnamma pits. There is a potential to utilize gnamma as an indicator of paleowind intensity because gnamma growth is promoted by the removal of particles from gnamma pits by wind, a process referred to as deflation. Wind tunnel tests determining the wind velocity threshold of deflation over a range of pit dimensions and particles sizes are conducted. Computational fluid dynamics (CFD) modeling utilizing the Re-Normalisation Group (RNG) K-Epsilon turbulence closure is used to investigate the distribution of wall shear stress and turbulent kinetic energy. An empirical equation is proposed to estimate shear stress as a function of the wind velocity and pit depth dimensions. With this equation and Shields Diagram, the wind velocity threshold for evacuating particles in the pit can be estimated by measuring the pit depth ratio and particle size. It is expected that the pit would continue to grow until this threshold is reached. The wind speed deflation threshold is smaller in the wind tunnel than predicted by the CFD and Shields diagram model. This discrepancy may be explained by the large turbulent kinetic energy in the gnamma pit as predicted by the CFD model as compared to the flat bed experiments used to define the Shields diagram. An empirical regression equation of the wind tunnel data is developed to estimate paleowind maximums.<br>Dissertation/Thesis<br>Masters Thesis Geography 2015

La seguente tesi di dottorato è incentrata sull’analisi teorica e sperimentale delle pompe utilizzate come turbine (comunemente chiamate in inglese Pumps as Turbines – PaTs). Il tema di ricerca è stato condotto in collaborazione con Nuovo Pignone Bari, che ha finanziato il progetto di ricerca stesso. Una PaT non è altro che una pompa convenzionale utilizzata come turbina al fine di recuperare energia (altrimenti persa) da flussi soggetti a considerevoli salti di pressione. Le PaT rappresentano una pratica alternativa alle turbine idrauliche progettate ad hoc sia per la complessità di quest’ultime, sia per l’ampia disponibilità di taglie standard e numeri di giri specifici delle pompe in commercio. Ovviamente, questa tecnologia risulta un’alternativa valida dal punto di vista tecnico – economico nel momento in cui si riesca a prevedere le performance in modalità inversa. Sfortunatamente i produttori di pompe non forniscono le caratteristiche delle loro macchine in modalità inversa, altrimenti il loro costo aumenterebbe significativamente. A causa di una evidente mancanza di dati sperimentali, numerosi studi sono stati condotti per realizzare modelli predittivi delle performance delle PaT. La maggior parte di questi modelli si focalizzano sulla previsione del BEP (Best Efficiency Point) e sono sviluppati per gli utenti che possono utilizzare semplici informazioni dai cataloghi commerciali (portata, prevalenza e rendimento di pompa al BEP). Per questo motivo, questi modelli sono abbastanza semplici e raramente considerano le condizioni di off-design. In aggiunta, essi mostrano una limitata applicabilità, mostrando errori di predizione del ± 20% ed essendo basati su correlazioni sperimentali su limitati campioni di macchine. Inoltre, i produttori per aumentare la loro competitività, necessitano di un tool che possa supportarli nella predizione del funzionamento turbina, partendo dalle caratteristiche delle loro pompe. Difatti i produttori posseggono dettagliate informazioni geometriche delle loro macchine, che possono risultare utili nello sviluppo di modelli più accurati. In questo scenario, il presente lavoro si pone l’obiettivo di sviluppare due modelli di predizione: (i) un modello sperimentale per la predizione del BEP della PaT, pensato come un tool di selezione per gli utenti; e (ii) un modello 1-D per la predizione dell’intera caratteristica della macchina. Il primo modello è stato proposto per gli utenti che vorrebbero selezione la miglior PaT per la loro specifica applicazione. Il modello è basato su un numero di campioni più alto rispetto ai casi presenti in letteratura al fine di ottenere una generale applicabilità nella predizione del BEP da turbina, riducendo l’errore di predizione del BEP al ± 10% rispetto ai modelli presenti in letteratura (± 20%). Il secondo modello è stato realizzato in collaborazione con Nuovo Pignone al fine di predire l’intera caratteristica della PaT. Esso è basato su dettagliate informazioni geometriche, perdite idrauliche e sul fenomeno dello scorrimento in uscita girante. Infine, il modello è stato validato su tre macchine di Nuovo Pignone, mostrando una maggiore accuratezza nella predizione dell’intera curva (± 4%) rispetto ad altri modelli in letteratura e al modello precedentemente sviluppato dall’azienda stessa. Durante il progetto di ricerca, è stato realizzato il set-up del banco prova sperimentale per pompe e turbine idrauliche presso il Dipartimento di Meccanica, Matematica e Management (DMMM) del Politecnico di Bari. Una pompa centrifuga è stata testata nel duplice funzionamento, al fine di utilizzare le caratteristiche sperimentali per sviluppare il modello sperimentale per la predizione del BEP e condurre un’analisi preliminare per l’installazione della stessa PaT in una rete idrica reale, presso Casamassima (Bari). Nella parte finale della tesi sono state analizzate le PaT multistadio operanti con fluidi bifase. In questo contesto, si è voluto sviluppare un metodo di validità generale che possa fornire le performance di una PaT operante con flusso bifase, partendo dalle caratteristiche con fluido monofase.<br>This PhD thesis is focused on theoretical and experimental analysis of Pumps as Turbines (PaTs). The PhD research project has been carried out in partnership with Nuovo Pignone Bari, a leader company in pump manufacturing, which founded this PhD scholarship. A PaT is a conventional pump used in reverse mode in order to recover energy, wasted otherwise, from flows subjected to considerable pressure drops. Due to the complexity of developing customized turbines, using pumps in reverse mode may represent a practical solution, in consideration of the wide range of specific speed numbers and available standard sizes of pumps. However, this technology is considered a cost-effective alternative to traditional turbines as long as their turbine mode performance can be predicted. Unfortunately, pump manufacturers do not usually offer performance curves of their pumps in reverse mode, since this requires testing of the machines also in turbine mode operation, hence increasing significantly their cost. Because of this lack of experimental data, a big number of studies can be found about the prediction of PaT performance but mainly focused on the turbine BEP (Best Efficiency Point). These prediction models are extremely simple but seldom consider off-design points. Furthermore, these models show a low applicability, showing prediction errors within ±20%, being usually based on experimental correlations from a limited number of samples. On the other side, pump manufacturers need of a tool that could support them to predict the turbine mode performance of their pumps by knowing pump characteristics, in order to be competitive on the market. In this landscape, the present work aims at developing two different prediction models: (i) an experimental model for the prediction of the BEP of PaTs, as a selection tool for users, which has showed a better accuracy (BEP prediction errors within ±10%) than the models found in literature in the turbine BEP prediction; (ii) and a new 1-D model for the prediction of the entire characteristic, as a design tool for manufactures, based on detailed geometrical information, hydraulic losses and the slip phenomenon at the outlet section of the runner. The model has been validated on three machines by Nuovo Pignone, showing a better accuracy in the prediction of their characteristics within ±4% than other models in literature and the pre-existing model developed by Nuovo Pignone. Moreover, a closed-loop test rig for experimental studies on hydraulic pumps and turbines has been set up. A KSB single-stage centrifugal pump has been tested in both direct and reverse modes. Experimental characteristic curves have been used to develop the experimental model for turbine BEP prediction, and to carry out a preliminary assessment of the installation of the same PaT in a real water distribution network in order to supply an electrical charging station. Finally, a theoretical approach has been proposed in order to predict the PaT performance with a two-phase flow, whose expansion characteristics are known.

One of the most widely used solar collectors for process heating and large scale electricity generation is the parabolic trough collector (PTC), in which a tube placed at the focus of the parabola receives concentrated solar radiation. In this work, a novel solar receiver design is proposed that bridges the gap in efficiency between the evacuated and non-evacuated receivers which are presently in use. In the standard or commercial non-evacuated receivers, the absorbing surface loses the heat to the surrounding ambient and to the heat transfer fluid (useful heat). A novel receiver has been proposed here, in which the absorbing surfaces (metal inserts) are immersed in the heat transfer fluid which is flowing through the inner tube of the receiver. The proposed design reduces the heat loss to the surrounding ambient. Experiments were conducted using water and air as heat transfer fluid (HTF), to compare the performance of the novel receiver with the standard receiver. Single pass experiments using water as HTF did not produce high fluid temperatures. In order to achieve higher fluid temperatures, experiments with recirculation of water were performed. The difference in the thermal performance of the novel receiver and the standard receiver became conspicuous as the losses became predominant. Also, it was observed that the thermal performance of the novel receiver over the standard receiver improved with an increase in the outlet temperature. Experiments using air as heat transfer fluid showed that the novel receiver outperformed the standard receiver in thermal performance. Also, the time response to changes in solar radiation was much lower for novel receiver as compared to standard receiver. Numerical simulations were performed using a one dimensional steady state heat transfer model for both these receivers. These results also indicate that the thermal performance of the novel receiver is superior to the standard receiver. Some interesting observations with regard to the influence of the heat transfer coefficient and incoming solar radiation on energy gain and loss have been noted and will be presented.